1. Field of the Invention
This invention relates to a swash-plate compressor to be used for an automobile air conditioning system.
2. Description of the Related Art:
There is a swash-plate compressor among compressors incorporated into an automobile air conditioning system to perform a compressing operation upon receipt of a rotational power of a vehicle engine. In the swash-plate compressor, a rotating motion of a shaft rotated upon receipt of a rotational power of the engine is converted into reciprocal motions of a plurality of pistons disposed around the shaft disposed in parallel thereto.
Due to this conversion of motions, a circular swash plate is mounted on the shaft to diagonally intersect the shaft, and each piston is provided with a dent for partially receiving the swash plate. The swash plate and each piston is in contact through bearing members disposed in the dent, and thrust bearings for reducing a rotary resistance of the swash plate is disposed around the shaft.
The swash plate rotates together with the shaft, and during the rotation, the position of each portion in the axial direction of the shaft relative to the peripheral direction of the swash plate varies. Consequently, each piston contacting the swash plate is forcibly displaced in the axial direction and reciprocates. As a result, in the automobile air-conditioning system, a refrigerant supplied from the exterior to the interior of the housing of the compressor is compressed, and the compressed refrigerant is discharged to the exterior of the housing.
In the swash-plate compressor, when its operation is started, the lubricating oil collected on the bottom of the housing partially enters the dent of each piston through the swash plate, while evaporating ingredients of the lubricating oil as well as the refrigerant enters the dent of each piston, to be used for lubrication between the swash plate and the bearing members as well as the thrust bearings. As a matter of fact, however, there were such cases as a seizure which occurred in a short time after an operation was started between the swash plate and the bearing member or between the race(s) and ball(s) of the thrust bearing, thereby stopping the operation of the compressor. This is because the supply of the lubricating oil between the swash plate and the bearing members as well as to the thrust bearings is not sufficient.
In view of this, it has been heretofore proposed to add another supply route for lubricating oil. The supply route includes a plurality of holes communicating with a screw hole provided at the shaft and opening at its one end and opening toward the thrust bearing (Japanese Patent Appln. PD No. 6-101641).
According to this, after the operation of the swash-plate compressor is started, evaporating ingredients of the lubricating oil on the bottom of the housing flow into the thread groove opening at one end of the shaft together with the refrigerant running inside the housing to be led from the thread groove to the thrust bearings and between the swash plate and the bearing members through the holes, and the lubricating oil attached to the thread groove and liquidized is fed into each hole through the thread groove, following the rotation of the shaft, to be supplied from the hole to the thrust bearings by the centrifugal force of the shaft, and furthermore, supplied between the swash plate and the bearings through the surface of the swash plate by the centrifugal force. Even by this, a seizure is sometimes caused, and the lubricating oil to these portions was not sufficiently refilled.